High-intensity focused ultrasound (HIFU) transducers are used to apply ultrasound energy to tissue in a manner that generates localized effects such as heating, boiling, or cavitation of tissue leading to ablation. Presently, HIFU power supplies are available that provide a broad range of driving characteristics. However, high-power (e.g., several kW), long (e.g., millisecond) pulse lengths are achievable only by large, expensive systems that are not feasible for typical clinical use. Emerging techniques, such as boiling histotripsy, require high-power delivery to the ultrasound transducer with long pulse lengths, outside the specifications of commercially available amplifiers. Thus, practical implementation of these techniques would benefit from an improved amplifier that provides these characteristics while retaining a small footprint and relatively low cost.